50 lines
1.3 KiB
C++
50 lines
1.3 KiB
C++
#include "RenderCadenceClock.h"
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#include <algorithm>
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RenderCadenceClock::RenderCadenceClock(double frameDurationMilliseconds)
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{
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mFrameDuration = std::chrono::duration_cast<Duration>(std::chrono::duration<double, std::milli>(frameDurationMilliseconds));
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if (mFrameDuration <= Duration::zero())
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mFrameDuration = std::chrono::milliseconds(16);
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Reset();
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}
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void RenderCadenceClock::Reset(TimePoint now)
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{
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mNextRenderTime = now;
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mPendingFrameAdvance = 1;
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mOverrunCount = 0;
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mSkippedFrameCount = 0;
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}
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RenderCadenceClock::Tick RenderCadenceClock::Poll(TimePoint now)
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{
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Tick tick;
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if (now < mNextRenderTime)
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{
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tick.sleepFor = std::min(Duration(std::chrono::milliseconds(1)), mNextRenderTime - now);
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return tick;
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}
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tick.due = true;
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mPendingFrameAdvance = 1;
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const Duration lateBy = now - mNextRenderTime;
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if (lateBy > mFrameDuration)
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{
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tick.skippedFrames = static_cast<uint64_t>(lateBy / mFrameDuration);
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mPendingFrameAdvance += tick.skippedFrames;
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++mOverrunCount;
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mSkippedFrameCount += tick.skippedFrames;
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}
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return tick;
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}
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void RenderCadenceClock::MarkRendered(TimePoint now)
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{
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mNextRenderTime += mFrameDuration * mPendingFrameAdvance;
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mPendingFrameAdvance = 1;
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if (now - mNextRenderTime > mFrameDuration * 4)
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mNextRenderTime = now + mFrameDuration;
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}
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